1. Field
This application relates to piano tuning hammers, a type of wrench used by piano tuners to adjust the pitch of a piano's strings.
2. Prior Art
Current Practice
A string in a piano is stretched between two pins: a hitch pin, which is fixed; and a tuning pins, which is moveable. A piano tuner adjusts the tension, and thereby the pitch, of a string by moving its attached tuning pin.
A tuning pin is a short, thick section of steel rod held by friction in a hole in a laminated wooden pin block. It has an exposed, squared head at one end, providing a means by which a piano tuner can engage it; a through hole, providing a means of attaching music wire to it; and a threaded portion which is gripped by the pin block, the threads providing a means of backing the tuning pin out of the pin block when necessary.
A tuning pin mounted in a pin block can move in two different ways: it can turn, and it can tilt. Broadly speaking, a piano tuner turns a tuning pin to effect a relatively large change in the pitch of its attached string; while he or she tilts it to effect a relatively small change in the attached string's pitch without further turning the pin. Both types of motion are used by professionals in piano tuning.
Extremely small changes in the position of a tuning pin typically result in significant changes in the pitch of its attached string. Therefore, the better control a tuner has over both the turning and tilting motions of a tuning pin, the better control he or she has over the pitch of the string.
Presently, all professional piano tuners use tuning hammers of the same general design. These conventional tuning hammers are shaped like the letter “L.” The short leg of the “L” comprises a tip region that engages the exposed, squared head of the tuning pin; and a head region, axial to the tip region, that elevates the tool above interfering structures in the piano. The long leg of the “L” comprises a shank region, substantially straight and substantially radial to the head region, that gives the operator adequate leverage to move the tuning pin without excessive effort; and a handle region that gives the operator a convenient and comfortable spot to which to apply force. U.S. Pat. No. 777,281 to Eklandsen (1904) depicts a tuning hammer which exemplifies this conventional “L” shape.
A necessary consequence of the elevated position of the shank and handle of a conventional tuning hammer is that some percentage of a turning force applied to its handle, intended to turn the tuning pin, is always diverted to tilting the tuning pin instead. A conventional tuning hammer can be manipulated so as to tilt a tuning pin without turning it, if the operator lifts or depresses its handle; however, the same tuning hammer cannot be manipulated so as to turn the pin without tilting it.
This prying effect is well-known to piano tuners. It is mentioned in many tuning textbooks and manuals, and many techniques of tuning hammer manipulation are designed to compensate for it. The effect is accurately described in U.S. patent application Ser. No. 11/004,215 from Fujan (2004) (Description, Background, Section [0008]):
“Since the handle of a tuning hammer is not in the same plane as the pin block, there will be a prying effect at the tuning pin, and consequently at the pin block. Reduction of this extra prying effect . . . serves to increase the predictability of the tuning process.”
This well-known inability of an operator of a conventional hammer to turn a tuning pin without tilting it poses an obstacle to the operator's ability finely to control the pitch of its attached string. It would be of great benefit to a piano tuner to be able to turn a tuning pin without tilting it, but such control is impossible with a conventional tuning hammer.
Prior Art Patents
No efforts in the prior art have gone towards reducing or eliminating the unintended tilting that accompanies every turning motion of a conventional tuning hammer, even though a number of patened tuning hammers do have as their stated purpose to give their operator greater control over the motions of the tuning pin.
A number of patents seek to improve the operator's control over the tuning pin by giving more options for the radial position of the handle than would be possible with a conventional tuning hammer. For example, U.S. Pat. No. 458,568 to Fuchs (1891) describes a tuning hammer with a double tip to provide the operator with twice as many possible handle positions than would be the case with a single tip. U.S. Pat. No. 140,450 to Affleck (1873) shows a tuning hammer in which a ratchet system accomplishes a similar goal.
Several patents seek to improve fine control over the turning of the tuning pin by increasing leverage. As an example, U.S. Pat. No. 1,693,292 to Frattenberger (1928) shows a tuning hammer provided with an offset connection between the shank and head with the stated purpose of increasing the tool's leverage. Other patents describe tuning hammers whose leverage is increased through the use of gears. For instance, U.S. Pat. No. 2,802,388 to Luckenbach (1957) describes a tool that uses gearing axial to the shank to increase fine control of the tuning pin.
U.S. Pat. No. 1,512,699 to Korach (1924) discloses a tool that uses gearing as well. In this instance, the tool itself is axial to the tuning pin, and therefore it does not tilt the tuning pin when the pin is turned. However, this advantage over conventional tuning hammers goes entirely unmentioned in the patent.
U.S. Pat. No. 2,751,805 to Leftly (1956) describes a tool that also uses gearing to increase leverage. The tip in this tool engages the pin near nearer its base than a conventional tip. As the patent notes, this reduces the tilting of the pin: “This [bending] effect is reduced to a minimum by engagement of the pin 11a with the inner flange 22a much closer to the base of the pin . . . ” (Description, Column 3, Lines 23-25). However, this reduction of bending or tilting of the pin is clearly seen as an ancillary benefit, and is not at all the purpose of the patent.
Failure of Prior Art Patents
None of these, or any other, patented improvements to the conventional tuning hammer have been adopted by those skilled in the art. None are mentioned in tool catalogs to the trade; and none are currently in use among professional piano tuners. Instead, every professional piano tuner uses a tuning hammer of the conventional “L” shape.
A prominent deficiency among the patented improvements is their inability to allow the operator directly to perceive the condition of the tuning pin. While tuning, a piano tuner not only continually monitors the pitch of the string being tuned, he or she also continually monitors the condition of the tuning pin. He or she does so because if the pin is not left free of residual stress at the end of the tuning process, it may move slightly after the hammer is removed, and thereby spontaneously change the pitch of its attached string.
A conventional tuning hammer generally has an overall rigidity which allows it to function, not only as a means of applying force, but also as a sensor. In order to be workable, in other words, a tuning hammer must be able not only to transfer force from its operator to the tuning pin; it must also be able to transfer information about the tuning pin back to its operator. By introducing a level of complexity and detachment between the tuning pin and the tuner, many of the prior art improvements reduce the ability of the tool to act as a sensor. Therefore, such tools function in practice less well than a simple, rigid, conventional tuning hammer.